Pub Date : 2022-10-26DOI: 10.17159/wsa/2022.v48.i4.3857
BC Scott-Shaw, R. Lechmere-Oertel, TR Hill
In South Africa, with highly variable and intense land-use practices, coupled with limited soil fertility and water resources, there has been a long history of encroachment of arable lands (sugarcane and timber plantations) into surrounding wetlands. Although wetland delineation within the timber and sugar sectors is well-defined in policy, and existing and proposed legislation, there are significant areas of non-compliance. The spatially-explicit Soil Water Assessment Tool (SWAT) was adopted to investigate the interactions of climate, land-use and soil on the water-use of natural and encroached wetlands. This paper documents the calibration, validation and application of the SWAT model on Quaternary Catchment (QC) U20G, which is a 498 km2 catchment that forms part of the uMngeni River basin. The SWAT-CUP parameter sensitivity and optimization model was tested with daily observed streamflow data for this catchment. Parameters were modified using the sequential uncertainty fitting (SUFI-2) analysis routine to calibrate the model. The simulated flow had a close fit to the observed flow with a regression coefficient (r2) of 0.87 and a Nash-Sutcliffe (NS) coefficient of 0.8. Through the buffer scenario analysis, the model showed that if the wetland and a 20-m buffer were to be returned to a natural state, there could be a 16% increase in the annual streamflow contribution, with an upper limit of a 60% increase in some hydrologic response units (HRUs). Thus there would be a hydrological gain if wetlands and sensitive buffer areas were to be cleared of commercial timber species and sugarcane.
{"title":"Calibration, validation and application of the SWAT model to determine the hydrological benefit of wetland rehabilitation in KwaZulu-Natal, South Africa","authors":"BC Scott-Shaw, R. Lechmere-Oertel, TR Hill","doi":"10.17159/wsa/2022.v48.i4.3857","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i4.3857","url":null,"abstract":"In South Africa, with highly variable and intense land-use practices, coupled with limited soil fertility and water resources, there has been a long history of encroachment of arable lands (sugarcane and timber plantations) into surrounding wetlands. Although wetland delineation within the timber and sugar sectors is well-defined in policy, and existing and proposed legislation, there are significant areas of non-compliance. The spatially-explicit Soil Water Assessment Tool (SWAT) was adopted to investigate the interactions of climate, land-use and soil on the water-use of natural and encroached wetlands. This paper documents the calibration, validation and application of the SWAT model on Quaternary Catchment (QC) U20G, which is a 498 km2 catchment that forms part of the uMngeni River basin. The SWAT-CUP parameter sensitivity and optimization model was tested with daily observed streamflow data for this catchment. Parameters were modified using the sequential uncertainty fitting (SUFI-2) analysis routine to calibrate the model. The simulated flow had a close fit to the observed flow with a regression coefficient (r2) of 0.87 and a Nash-Sutcliffe (NS) coefficient of 0.8. Through the buffer scenario analysis, the model showed that if the wetland and a 20-m buffer were to be returned to a natural state, there could be a 16% increase in the annual streamflow contribution, with an upper limit of a 60% increase in some hydrologic response units (HRUs). Thus there would be a hydrological gain if wetlands and sensitive buffer areas were to be cleared of commercial timber species and sugarcane.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88571943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-26DOI: 10.17159/wsa/2022.v48.i4.3944
N. James, Td Harrison
A preliminary ichthyofaunal and physico-chemical survey of estuaries on the east coast of South Africa from the Mpande Estuary to the Mtentwana Estuary was undertaken between November 1997 and January 1998. Sixteen estuaries were surveyed along this stretch of coastline and these were grouped into three estuary types: small (< 10 ha) predominantly closed estuaries, moderate to large (> 10 ha) predominantly closed estuaries and predominantly open estuaries. Multivariate analyses revealed significant differences between the three groups in terms of both their physico-chemical characteristics (small predominantly closed estuaries were different from predominantly open estuaries) and their fish communities (all three estuary types were significantly different). The estuaries in the study area fall within the subtropical/warm-temperate transition-zone and north of the subtropical/warm-temperate biogeographic break; tropical species dominated the fish communities of all the estuaries in terms of numbers of species and biomass. This survey represents one of the few fish surveys undertaken along this little-studied section of the coastline.
{"title":"A preliminary fish survey of the estuaries on the east coast of South Africa, Mpande to Mtentwana: a comparative study","authors":"N. James, Td Harrison","doi":"10.17159/wsa/2022.v48.i4.3944","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i4.3944","url":null,"abstract":"A preliminary ichthyofaunal and physico-chemical survey of estuaries on the east coast of South Africa from the Mpande Estuary to the Mtentwana Estuary was undertaken between November 1997 and January 1998. Sixteen estuaries were surveyed along this stretch of coastline and these were grouped into three estuary types: small (< 10 ha) predominantly closed estuaries, moderate to large (> 10 ha) predominantly closed estuaries and predominantly open estuaries. Multivariate analyses revealed significant differences between the three groups in terms of both their physico-chemical characteristics (small predominantly closed estuaries were different from predominantly open estuaries) and their fish communities (all three estuary types were significantly different). The estuaries in the study area fall within the subtropical/warm-temperate transition-zone and north of the subtropical/warm-temperate biogeographic break; tropical species dominated the fish communities of all the estuaries in terms of numbers of species and biomass. This survey represents one of the few fish surveys undertaken along this little-studied section of the coastline.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79369253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-26DOI: 10.17159/wsa/2022.v48.i4.3986
A. Joubert, FP Retief, N. Smit, RC Alberts, V. Wepener, C. Roos
Freshwater recreational angling is growing in popularity internationally. Due to the potential negative environmental impacts, various regulatory systems exist. In South Africa, freshwater recreational angling is regulated through a complex legal framework, consisting of national and provincial legislation dating back to the 1960s. The legislation also relates to historical and current provincial boundaries, adding to the regulatory complexity. Due to this complexity, the question arises whether freshwater recreational bank anglers in South Africa are aware of the regulatory requirements applicable to them. Low levels of awareness could lead to non-compliance, which would suggest an ineffective regulatory system. The aim of this research was thus to determine the environmental regulatory awareness of freshwater recreational bank anglers in South Africa. This was achieved through a literature review of national and provincial legislation, as well as the rules applicable to organised freshwater recreational bank angling. An online survey was completed by 100 members of the South African Freshwater Bank Angling Federation (SAFBAF). The results of the survey indicate that the regulatory awareness of the sample of SAFBAF freshwater recreational anglers is low in certain key areas, such as bag and size limits for specific fish species, catch and release requirements, as well as legal definitions for alien and invasive and TOPS species listings. However, the low level of awareness can be ascribed to the complex regulatory system and not unwillingness of anglers to comply per se. It is recommended that (i) a single consolidated and simplified regulatory system for freshwater recreational bank angling be developed, and (ii) that angling organisational and competition rules be aligned with relevant regulatory requirements, to improve overall awareness and promote higher levels of regulatory compliance.
{"title":"Environmental regulatory awareness of freshwater recreational bank anglers in South Africa","authors":"A. Joubert, FP Retief, N. Smit, RC Alberts, V. Wepener, C. Roos","doi":"10.17159/wsa/2022.v48.i4.3986","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i4.3986","url":null,"abstract":"Freshwater recreational angling is growing in popularity internationally. Due to the potential negative environmental impacts, various regulatory systems exist. In South Africa, freshwater recreational angling is regulated through a complex legal framework, consisting of national and provincial legislation dating back to the 1960s. The legislation also relates to historical and current provincial boundaries, adding to the regulatory complexity. Due to this complexity, the question arises whether freshwater recreational bank anglers in South Africa are aware of the regulatory requirements applicable to them. Low levels of awareness could lead to non-compliance, which would suggest an ineffective regulatory system. The aim of this research was thus to determine the environmental regulatory awareness of freshwater recreational bank anglers in South Africa. This was achieved through a literature review of national and provincial legislation, as well as the rules applicable to organised freshwater recreational bank angling. An online survey was completed by 100 members of the South African Freshwater Bank Angling Federation (SAFBAF). The results of the survey indicate that the regulatory awareness of the sample of SAFBAF freshwater recreational anglers is low in certain key areas, such as bag and size limits for specific fish species, catch and release requirements, as well as legal definitions for alien and invasive and TOPS species listings. However, the low level of awareness can be ascribed to the complex regulatory system and not unwillingness of anglers to comply per se. It is recommended that (i) a single consolidated and simplified regulatory system for freshwater recreational bank angling be developed, and (ii) that angling organisational and competition rules be aligned with relevant regulatory requirements, to improve overall awareness and promote higher levels of regulatory compliance.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87845470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-26DOI: 10.17159/wsa/2022.v48.i4.3977
JJ van Tol, GM van Zijl
Accurate hydrological modelling to evaluate the impacts of climate and land use change on water resources is pivotal to sustainable management. Soil information is an important input in hydrological models but is often not available at adequate scale with appropriate attributes for direct parameterisation of the models. In this study, conducted in three quaternary catchments in the midlands of KwaZulu-Natal, three different soil information sets were used to configure SWAT+, a revised version of the Soil and Water Assessment Tool (SWAT). The datasets were: (i) the Land Type database (currently the only soil dataset covering the whole of South Africa), (ii) disaggregation of the Land Type database using digital soil mapping techniques (called DSMART), and (iii) a dataset where DSMART were complemented by field observations and interpretations of the hydropedological behaviour of the soils (DSMART+). Simulated streamflow was compared with measured streamflow at three weirs with long-term measurements, and the impact of the soil datasets on water balance simulations was evaluated. In general, the simulations were acceptable when compared to other studies, but could be improved through calibration and including small reservoirs in the model. The DSMART+ dataset yielded more accurate simulations of streamflow in all three catchments with Nash-Sutcliffe efficiencies increasing by between 9% and 67% when compared to the Land Type dataset. The value of the improved soil maps is, however, highlighted through the enhanced spatial detail of streamflow generation mechanisms and water balance components. The internal catchment processes are represented more accurately, and we argue that South Africa needs a detailed hydrological soil map for effective water resource management.
{"title":"South Africa needs a hydrological soil map: a case study from the upper uMngeni catchment","authors":"JJ van Tol, GM van Zijl","doi":"10.17159/wsa/2022.v48.i4.3977","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i4.3977","url":null,"abstract":"Accurate hydrological modelling to evaluate the impacts of climate and land use change on water resources is pivotal to sustainable management. Soil information is an important input in hydrological models but is often not available at adequate scale with appropriate attributes for direct parameterisation of the models. In this study, conducted in three quaternary catchments in the midlands of KwaZulu-Natal, three different soil information sets were used to configure SWAT+, a revised version of the Soil and Water Assessment Tool (SWAT). The datasets were: (i) the Land Type database (currently the only soil dataset covering the whole of South Africa), (ii) disaggregation of the Land Type database using digital soil mapping techniques (called DSMART), and (iii) a dataset where DSMART were complemented by field observations and interpretations of the hydropedological behaviour of the soils (DSMART+). Simulated streamflow was compared with measured streamflow at three weirs with long-term measurements, and the impact of the soil datasets on water balance simulations was evaluated. In general, the simulations were acceptable when compared to other studies, but could be improved through calibration and including small reservoirs in the model. The DSMART+ dataset yielded more accurate simulations of streamflow in all three catchments with Nash-Sutcliffe efficiencies increasing by between 9% and 67% when compared to the Land Type dataset. The value of the improved soil maps is, however, highlighted through the enhanced spatial detail of streamflow generation mechanisms and water balance components. The internal catchment processes are represented more accurately, and we argue that South Africa needs a detailed hydrological soil map for effective water resource management.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87812303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-26DOI: 10.17159/wsa/2022.v48.i4.3930
Elif İnce, M. Ince, Handenur Yaşar, Yasin Abdullah Uslu
In the membrane distillation bioreactor (MDBR) process, flux increases with increasing feed temperature, but the presence of microorganisms limits the feed temperature. Also, the accumulation of cells and other substances on the membrane surface can affect the efficiency of MDBR. In this study, hospital wastewater was treated by thermophilic activated sludge MDBR. In the MDBR, the initial flux was 7.87 L‧m−2·h−1 and the stable flux was 3.88 L‧m−2·h−1. The particle size, zeta potential and hydrophobicity of the activated sludge in MDBR were 2.25 µm, −14 mV and 24%, respectively. In addition, EPS (extracellular polymeric substances) and SMP (soluble microbial products), having a significant effect on membrane fouling, were determined to be 201.50 mg·L−1 and 669.35 mg·L−1 in MDBR, respectively. Contact angle, FTIR (Fourier transform infrared), SEM (scanning electron microscope) and EDX (energy dispersive X-ray spectroscopy) measurements were also made on a virgin membrane and used membrane. Analysis of EDX, SEM and F-TIR showed that the membrane fouling was caused by CaCO3 and EPS.
{"title":"Membrane fouling in thermophilic aerobic membrane distillation bioreactor treating hospital wastewater","authors":"Elif İnce, M. Ince, Handenur Yaşar, Yasin Abdullah Uslu","doi":"10.17159/wsa/2022.v48.i4.3930","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i4.3930","url":null,"abstract":"In the membrane distillation bioreactor (MDBR) process, flux increases with increasing feed temperature, but the presence of microorganisms limits the feed temperature. Also, the accumulation of cells and other substances on the membrane surface can affect the efficiency of MDBR. In this study, hospital wastewater was treated by thermophilic activated sludge MDBR. In the MDBR, the initial flux was 7.87 L‧m−2·h−1 and the stable flux was 3.88 L‧m−2·h−1. The particle size, zeta potential and hydrophobicity of the activated sludge in MDBR were 2.25 µm, −14 mV and 24%, respectively. In addition, EPS (extracellular polymeric substances) and SMP (soluble microbial products), having a significant effect on membrane fouling, were determined to be 201.50 mg·L−1 and 669.35 mg·L−1 in MDBR, respectively. Contact angle, FTIR (Fourier transform infrared), SEM (scanning electron microscope) and EDX (energy dispersive X-ray spectroscopy) measurements were also made on a virgin membrane and used membrane. Analysis of EDX, SEM and F-TIR showed that the membrane fouling was caused by CaCO3 and EPS.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81786983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Interest in greywater reuse is increasing in South Africa, because of the potential to supplement scarce freshwater resources in the face of increasing demand and aridity. This paper aims to inform the water saving–risk trade-off associated with residential untreated greywater use, through a statistical analysis of greywater quality results as sourced from prior South African studies. Greywater sources included in this review were the bathroom, kitchen, laundry, mixed and general residential sources. Variability in terms of each of the reported physical, chemical and microbiological constituents by source and between result sets was noted. Statistically significant differences were evident between the pH, conductivity and phosphorus values of certain sources. A risk assessment undertaken for each of the constituents revealed further variability. The constituent with the highest number of high-risk samples was total dissolved solids. The relatively high risk and negative consequences in greywater practices in terms of public health, the environment, and infrastructure, given this variability, provide insight into the trade-off with potential water savings. It is recommended that a more nuanced view of the potential potable savings associated with greywater reuse and also improved risk management is required by the user.
{"title":"A review of untreated household greywater quality to inform the water saving–risk trade-off in South Africa","authors":"Heinz Erasmus Jacobs, Nicole Nel, Isobel Brink, Adesola Ilemobade","doi":"10.17159/wsa/2022.v48.i4.3946","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i4.3946","url":null,"abstract":"Interest in greywater reuse is increasing in South Africa, because of the potential to supplement scarce freshwater resources in the face of increasing demand and aridity. This paper aims to inform the water saving–risk trade-off associated with residential untreated greywater use, through a statistical analysis of greywater quality results as sourced from prior South African studies. Greywater sources included in this review were the bathroom, kitchen, laundry, mixed and general residential sources. Variability in terms of each of the reported physical, chemical and microbiological constituents by source and between result sets was noted. Statistically significant differences were evident between the pH, conductivity and phosphorus values of certain sources. A risk assessment undertaken for each of the constituents revealed further variability. The constituent with the highest number of high-risk samples was total dissolved solids. The relatively high risk and negative consequences in greywater practices in terms of public health, the environment, and infrastructure, given this variability, provide insight into the trade-off with potential water savings. It is recommended that a more nuanced view of the potential potable savings associated with greywater reuse and also improved risk management is required by the user.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82259752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3872
Germaine Owen, Horman Chitonge
The recent drought in the Western Cape Province in South Africa has been marked as the worst since 1904. The drought impacted severely on the availability of bulk water supply in many parts of the Western Cape Province, particularly the Cape Town Metro and surrounding districts. In order to alleviate water scarcity, wastewater recycling (water reuse) has been identified to have the potential to augment water supplies in the province. This paper argues that although water recycling has the potential to contribute towards alleviating water scarcity, studies have shown that public perceptions greatly influence the outcome of any water recycling scheme. The study collected data using face-to-face interviews, focus group discussions, and the application of the Story with a Gap participatory exercise. One of the key findings is that residents have to trust the municipal competencies and systems, and this can be achieved through meaningful engagement between the municipality and residents. We argue that rolling out a water reuse scheme by starting with affluent areas increases the likelihood of acceptance among low-income communities.
{"title":"Public perception of water re-use: building trust in alternative water sources in Malmesbury, South Africa","authors":"Germaine Owen, Horman Chitonge","doi":"10.17159/wsa/2022.v48.i3.3872","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3872","url":null,"abstract":"The recent drought in the Western Cape Province in South Africa has been marked as the worst since 1904. The drought impacted severely on the availability of bulk water supply in many parts of the Western Cape Province, particularly the Cape Town Metro and surrounding districts. In order to alleviate water scarcity, wastewater recycling (water reuse) has been identified to have the potential to augment water supplies in the province. This paper argues that although water recycling has the potential to contribute towards alleviating water scarcity, studies have shown that public perceptions greatly influence the outcome of any water recycling scheme. The study collected data using face-to-face interviews, focus group discussions, and the application of the Story with a Gap participatory exercise. One of the key findings is that residents have to trust the municipal competencies and systems, and this can be achieved through meaningful engagement between the municipality and residents. We argue that rolling out a water reuse scheme by starting with affluent areas increases the likelihood of acceptance among low-income communities.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80521721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3933
E Öztekin, S Çolak, H İnan
Human urine constitutes 1% of domestic wastewater and can be used to recover nitrogen and phosphorus when collected separately at source. Sustainable nutrient (nitrogen, phosphate, potassium) cycling requires the recovery of these valuable resources from human urine. As nitrogen and phosphorus are valuable nutrients needed for plant growth, these components of urine are an excellent fertilizer. Phosphorus can be applied in natural fertilizers and in addition the pollution load of wastewater treatment plants is reduced. Different nutrient removal and recovery methods from urine have been studied at lab scale, but none so far has reached technological competence and none has been extended to practical use. The focus of this study was to evaluate electrocoagulation as a process for the removal of phosphate from fresh human urine using iron plate electrodes. The effect of pH and current density on phosphate removal was investigated. While determining the optimum conditions for removal, classical and chemometric methods were compared. Using the central composite design (CCD), optimum conditions were determined with only 13 experiments, and time and labour savings were achieved compared to the classical method. Initial pH values and current density were controlled within the range of pH 5–9 and current density 12-40 mA/cm2. From the obtained results, it was found that optimal initial current density is 40 mA/cm2 for both methods, and optimal pH is 7 for the classical method and 6.24 for CCD, which is the natural pH of human urine. Realization of phosphate removal using optimum conditions discovered with CCD, provides savings on experimental effort, time, chemicals and energy consumption, and will contribute to resource recovery, reduction of wastewater load and sustainable fertilizer production.
{"title":"Comparison of classic and chemometric methods used for phosphate removal from fresh human urine under optimum conditions","authors":"E Öztekin, S Çolak, H İnan","doi":"10.17159/wsa/2022.v48.i3.3933","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3933","url":null,"abstract":"Human urine constitutes 1% of domestic wastewater and can be used to recover nitrogen and phosphorus when collected separately at source. Sustainable nutrient (nitrogen, phosphate, potassium) cycling requires the recovery of these valuable resources from human urine. As nitrogen and phosphorus are valuable nutrients needed for plant growth, these components of urine are an excellent fertilizer. Phosphorus can be applied in natural fertilizers and in addition the pollution load of wastewater treatment plants is reduced. Different nutrient removal and recovery methods from urine have been studied at lab scale, but none so far has reached technological competence and none has been extended to practical use. The focus of this study was to evaluate electrocoagulation as a process for the removal of phosphate from fresh human urine using iron plate electrodes. The effect of pH and current density on phosphate removal was investigated. While determining the optimum conditions for removal, classical and chemometric methods were compared. Using the central composite design (CCD), optimum conditions were determined with only 13 experiments, and time and labour savings were achieved compared to the classical method. Initial pH values and current density were controlled within the range of pH 5–9 and current density 12-40 mA/cm2. From the obtained results, it was found that optimal initial current density is 40 mA/cm2 for both methods, and optimal pH is 7 for the classical method and 6.24 for CCD, which is the natural pH of human urine. Realization of phosphate removal using optimum conditions discovered with CCD, provides savings on experimental effort, time, chemicals and energy consumption, and will contribute to resource recovery, reduction of wastewater load and sustainable fertilizer production.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85893200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3885
Beaven Utete, Olga Laiza Kupika, Precious Mahlatini, Tapiwa Nyachowe
The conservation status of inland fishery resources is vulnerable worldwide, and this threatens the livelihoods of fishing-dependent communities. This case study aimed to: (i) establish the use and perception of fisheries and ecosystem services by locals, (ii) undertake a monetary valuation of the fisheries, (iii) determine the potential threats to the fisheries, and (iv) examine the social drivers and barriers for citizen science involvement. Lastly, (v) we evaluated how the above factors affected the conservation of fisheries at Mushumbi Pools, Zimbabwe. A cross-sectional survey of 69 households was conducted. Results of the study showed that locals utilised 17 fish species for social, economic, cultural and religious purposes. Locals attach high intrinsic socio-economic value to the fisheries resources and wetland ecosystem services provided by the Mushumbi Pools. Despite the sustained income from fisheries, the local market in Mushumbi Pools is actually undervaluing fisheries resources, as the fish prices in the area are very low compared to standard market prices countrywide. A larger proportion of the respondents (65%) cited poor land-tilling practices, heavy application of agropesticides and use of unsustainable fish harvesting methods as the main threats to fish diversity in Mushumbi Pools. Relaxed fishing concessions for women and children in specific fishing zones were key drivers for community participation in fisheries conservation. However, strict enforcement of fishing bans in breeding and nursery zones and restricted access to some parts of the Mushumbi Pools were the main barriers for local involvement in the conservation of fisheries resources. Without the fishing community’s participation there is no guaranteed sustainability of the fishery resources in the pools. Legitimising community access, ensuring fair valuation and utility rights is a key driver for successful management of inland fisheries resources in Sub-Saharan Africa.
{"title":"How local communities access, utilise and evaluate inland fisheries, and their influence on fishery conservation status in northern Zimbabwe","authors":"Beaven Utete, Olga Laiza Kupika, Precious Mahlatini, Tapiwa Nyachowe","doi":"10.17159/wsa/2022.v48.i3.3885","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3885","url":null,"abstract":"The conservation status of inland fishery resources is vulnerable worldwide, and this threatens the livelihoods of fishing-dependent communities. This case study aimed to: (i) establish the use and perception of fisheries and ecosystem services by locals, (ii) undertake a monetary valuation of the fisheries, (iii) determine the potential threats to the fisheries, and (iv) examine the social drivers and barriers for citizen science involvement. Lastly, (v) we evaluated how the above factors affected the conservation of fisheries at Mushumbi Pools, Zimbabwe. A cross-sectional survey of 69 households was conducted. Results of the study showed that locals utilised 17 fish species for social, economic, cultural and religious purposes. Locals attach high intrinsic socio-economic value to the fisheries resources and wetland ecosystem services provided by the Mushumbi Pools. Despite the sustained income from fisheries, the local market in Mushumbi Pools is actually undervaluing fisheries resources, as the fish prices in the area are very low compared to standard market prices countrywide. A larger proportion of the respondents (65%) cited poor land-tilling practices, heavy application of agropesticides and use of unsustainable fish harvesting methods as the main threats to fish diversity in Mushumbi Pools. Relaxed fishing concessions for women and children in specific fishing zones were key drivers for community participation in fisheries conservation. However, strict enforcement of fishing bans in breeding and nursery zones and restricted access to some parts of the Mushumbi Pools were the main barriers for local involvement in the conservation of fisheries resources. Without the fishing community’s participation there is no guaranteed sustainability of the fishery resources in the pools. Legitimising community access, ensuring fair valuation and utility rights is a key driver for successful management of inland fisheries resources in Sub-Saharan Africa.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91251246","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-27DOI: 10.17159/wsa/2022.v48.i3.3911
Hossein Elahifar, Omid Tayari, Najme Yazdanpanah, Mehdi Momeni
This study investigated the discharge coefficient in asymmetric rectangular labyrinth weirs. A dimensional analysis was carried out which showed that the discharge coefficient is a function of dimensionless parameters, such as the ratio of asymmetric widths of left and right cycles (wL/wR), the ratio of the total hydraulic head to the weir height (Ht/P), and the weir length ratio (B/wavg). The experimental results for the discharge coefficient were found to decline as wL/wR increased or B/wavg decreased. For wL/wR = 1.19, the ratio B/wavg = 2.76 improves the discharge coefficient by nearly 12.7% compared to B/wavg = 3.1. For wL/wR = 1.42, the ratio B/wavg = 2.76 improves the discharge coefficient by nearly 34.2% compared to B/wavg = 3.1. For wL/wR = 1.70, the ratio B/wavg = 2.76 improves the discharge coefficient by nearly 30% compared to B/wavg = 3.1.
{"title":"Experimental investigation of the discharge coefficient of labyrinth weirs with asymmetric cycles","authors":"Hossein Elahifar, Omid Tayari, Najme Yazdanpanah, Mehdi Momeni","doi":"10.17159/wsa/2022.v48.i3.3911","DOIUrl":"https://doi.org/10.17159/wsa/2022.v48.i3.3911","url":null,"abstract":"This study investigated the discharge coefficient in asymmetric rectangular labyrinth weirs. A dimensional analysis was carried out which showed that the discharge coefficient is a function of dimensionless parameters, such as the ratio of asymmetric widths of left and right cycles (wL/wR), the ratio of the total hydraulic head to the weir height (Ht/P), and the weir length ratio (B/wavg). The experimental results for the discharge coefficient were found to decline as wL/wR increased or B/wavg decreased. For wL/wR = 1.19, the ratio B/wavg = 2.76 improves the discharge coefficient by nearly 12.7% compared to B/wavg = 3.1. For wL/wR = 1.42, the ratio B/wavg = 2.76 improves the discharge coefficient by nearly 34.2% compared to B/wavg = 3.1. For wL/wR = 1.70, the ratio B/wavg = 2.76 improves the discharge coefficient by nearly 30% compared to B/wavg = 3.1.","PeriodicalId":23623,"journal":{"name":"Water SA","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86843354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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